This is definitely (hopefully) something you would not see today. It’s a large parade of tanks heading from the Capitol Building towards the White House.
Source: National Geographic
The caption claims it’s 1947, but the discussion on Reddit seem to point to a time during World War II.
This is early WW2… 1942 or possibly early 1943. This is a much smaller model than the Sherman, which reached its production peak in 1944.
Source: http://natgeofound.tumblr.com/post/52966623825/u-s-military-tanks-parade-near-the-capitol PHOTOGRAPH BY VOLKMAR K. WENTZEL, NATIONAL GEOGRAPHIC
They are either M3 or M5 Light Tanks – Stuart’s I believe. These would have been very early in the war. If later, they might have been training units for National Guard Troops.